Device for fusing electrodes into tubes



June 17, 1958 .o. BACHMANN 2,838,878

DEVICE FOR FUSING ELECTRODES INTO TUBES Filed Feb. 10 1954 Fig.2

N W Mmmw MT T W3 A $1 M W m E Q a r 2,838,878 Patented June 17, 1958 DEVICE FOR FUSING ELECTRODES INTO TUBES Oskar Bachmaun, Kaiserstuhl, Switzerland Application February 10, 1954, Serial No. 409,465 Claims priority, application Switzerland February 18, 1953 6 Claims. (Cl. 49-7) The invention relates to combined heating and pressing glassworking apparatus suitable for the fusing of electrodes into tubes, for example, the sealing of lead wires in. the stems of electric incandescent lamps, wherein the glass or quartz of the tube is softened by the heat of gas jets, and pressure is applied by means of jaws to opposite sides of the hollowtube, the tube being heated and softened by gas jets so that the tube is collapsed laterally and the lead wires or electrodes are thereby fused into the softened vitreous material to provide a permanent seal.

These jaws are hollow and are connected to a source ofsupp'ly of a combustion gas and have discharge openings from which'jets of flaming gas are directed towards the portions of the hollow tube which are to be squeezed gether between thejaws. Usually these openings are so arranged that the said gas jets are directed toward the workpiece substantially along the direction ofrectilinear movement of the said jaws as they close upon the workpiece. This has the unfavorable consequence that the particular portions of the tube or lamp which are to be deformed least are heated most, and conversely those spots which are to be deformed most are heated least.

It is the main object of the present invention to provide a device for the fusing of electrodes or lead wires into tubes, for example into glass or quartz tubes of incandescent wire lamps, wherein those portions of the tube which are to be deformed most and are therefore the softest in the squeezing process are also heated most.

It is another object of the invention to provide a device 7 of the kind referred to wherein the combined heating and squeezing jaws are cooled in a simple and effective manner.

With these and other objects in view I provide a device for the fusing of electrodes or lead wires into hollow glass or quartz tubes, comprising in combination: a pair of hollow jaws arranged for rectilinear movement toward and away from each other, each jaw having a workpiece engaging pressing face transverse to the direction of their mutual movement and a heating or gas burner face inclined but slightly to the direction of jaw movement, and an inner duct connected in operation to a source of supply of combustion gas and in communication with burner discharge openings provided in the said slightly inclined face, the jets of the said combustion gas emerging, in

operation, from the said discharge openings substantially transversely to the direction of jaw movement.

Preferably the said jaws are double-walled, the said inner duct leading the combustion gas to the burner discharge openings, and a surrounding cooling jacket being connected in operation to the supply and drain, respectively, of a source of coolant, the said coolant flowing in operation around the said inner duct and along the inner faces of the outer walls of the said jaws.

These and other objects and features of my invention will become clearly apparent from the following description of an embodiment thereof given by way of example and with reference to the accompanying drawing, in which:

Fig. l is a longitudinal section through a single jaw,

Fig. 2 is a plan view of Fig. l, and

Fig. 3 shows on a smaller scale two cooperating jaws in the operative or workpiece engaging position, in plan view.

Each of the cooperating jaws 1, 2 (Fig. 3) is connected to a fuel supply pipe 3 for the combustion gas. The supply pipe 3 is connected to an inner duct 4 arranged in the interior of the jaw (Fig. 1) and communicating with gas burner discharge openings 5. To each jaw a supply pipe 6 and drain pipe 7 for a coolant, for example water, is attached which circulates in a cooling jacket surrounding the inner duct 4 and flows along the inner faces of the outer walls of the said jaw. I

The jaws 1, 2 have, as usual, pressing'faces' 8, 9, respectively, which extend transversely with respect to the direction of movement of thesaid jaws relative to one another when they move toward each other as indicated in Fig. 3 by the arrows, and perforated burner faces 10, 11, respectively, generally parallel to but inclined at small angles with respect to the directionof jaw movement. The burner openings 5 from the inner duct 4 are so arranged on the burner faces lil, 11 (Figs. 1 and 2), that the flaming gas jets emerging from these openings are directed substantially transversely with respect to the direction of rectilinear movement of the said jaws toward each other during the squeezing operation. I

When, for example, a cylindrical end of a tube or other vitreous workpiece into which electrodes are to be fused, is inserted between the said jaws 1, 2 (as indicated diagrammatically in Fig. 3) the lateral portions of the tube which are nearest to the confronting burner faces 10, 11 are heated most. These lateral portions of the workpiece which are heated the most will of course be H the softest and the most easily deformed. These softest lateral portions, however, are not the portions which are directly engaged by the jaws, but are those portions which are bent or deformed the most during the squeezing ofthe workpiece between the pressing faces 8, 9 of the jaws. A relatively slight flattening of the portions of the workpiece which are in direct contact with the press ing faces 8, 9 is all that is required. Accordingly, this slight flattening does not require the greatest amount of heat. The adjacent lateral portions which are nearest to the burner faces 9 and 10 undergo a much greater bending deformation and should therefore be the softest.

' The novel jaw structure of the present invention inherently provides for this desirable condition.

The embodiment illustrated dispenses with the provision of special cooling chambers for the jaws, the latter being double-Walled'and serving themselves as coolant jackets, whereby the production is simplified, and the cooling is made more effective.

While I have herein described and illustrated in the accompanying drawing what may be considered a typical and particularly useful embodiment of my said invention, I Wish it to be understood that I do not limit myself to the particular details and dimensions described and illustrated, for obvious modifications will occur to a person skilled in the art.

What I claim as my invention and desire to secure by Letters Patent, is:

1'. A device for fusing electrodes into deformable tubes, comprising in combination: a pair of hollow jaws arranged for rectilinear movement toward and away from one another, each jaw having a pressing face transverse to the direction of said movement and -a burner face inclined at not more than a slight angle to the said direction and having discharge openings, and an inner duct connected-in operation to a source of supply of combustion gas and being in communication with the discharge openings provided in the said inclined burner face, the

jets of the said combustion gas emerging in operation from the said discharge openings in a direction substantially transversely to the said direction of movement.

2. A device for fusing electrodes into deformable tubes, comprising in combination: a pair of hollow doublewalled jaws arranged for rectilinear movement toward and away from one another, each jaw having a pressing face extending transversely with respect to the di rection of said movement and a burner face slightly inclined to the said direction and having discharge openings therein, each jaw having an inner duct connected in operation to a source of supply of combustion gas and in communication with the discharge openings provided in the said inclined face, the walls of each jaw and its ductforming a jacket connected in operation to the supply and drain pipes of a coolant, the said coolant flowing in operation around the said inner duct and along the inner face of the outer wall of the said double-walled jaw, and flaming jets of the said combustion gas emerging in operation from the said discharge openings substantially transversely to the said direction of movement.

3. A device for fusing electrodes into deformable tubes, comprising in combination, a pair of hollow rectilinearly movable cooperating pressure jaws, the jaws having a pair of opposed pressing faces disposed transversely to the direction of movement of the jaws and having another pair of confronting burner faces each disposed substantially at right angles to one of said pressing faces, said burner working faces having a plurality of discharge Cir openings arranged to discharge flaming jets of combustion gas in a direction transverse to the direction of relative moveemnt of the jaws, said jaws being provided with conduits for conducting gas into the interior thereof and through said discharge openings.

4. A device according to claim 3, in which each of said burner faces are inclined at a slightly obtuse angle with respect to one of said pressing faces.

5. Apparatus of the class described for softening and pressing a workpiece which is deformable when heated, said apparatus comprising a pair of cooperating jaw members, at least one of said jaw members being rectilinearly movable along a direction extending between said jaw members for engaging and pressing said workpiece therebetween, burner means included in each jaw member, each burner means being adapted to project a gas flame transversely said direction and toward the other burner means for simultaneously softening opposite sides of said workpiece, each of said jaw members comprising a pressing surface which extends transversely of said direction, said pressing surfaces confronting each other for simultaneous engagement with opposite sides of said workpiece which are adjacent to the sides thereof which are softened by said burner means.

6. Apparatus according to claim 4, in which said burner means each comprises an apcrtured portion of one of said jaw members, each of said apertured portions directing said gas flame in a direction having a component directed along said first-named direction and away from the pressing surface of its associated jaw member for permitting said workpiece to be heated and softened without being engaged by said pressing surfaces.

References Cited in the file of this patent UNITED STATES PATENTS 

